/*
 *    Copyright 2009-2012 the original author or authors.
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */
package org.apache.ibatis.session.defaults;

import org.apache.ibatis.exceptions.ExceptionFactory;
import org.apache.ibatis.executor.ErrorContext;
import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.mapping.Environment;
import org.apache.ibatis.session.*;
import org.apache.ibatis.transaction.Transaction;
import org.apache.ibatis.transaction.TransactionFactory;
import org.apache.ibatis.transaction.managed.ManagedTransactionFactory;

import java.sql.Connection;
import java.sql.SQLException;

/**
 * @author Clinton Begin
 */
public class DefaultSqlSessionFactory
        implements SqlSessionFactory {

    private final Configuration configuration;

    public DefaultSqlSessionFactory(
            Configuration configuration) {
        this.configuration = configuration;
    }

    public SqlSession openSession() {
        return openSessionFromDataSource(
                configuration
                        .getDefaultExecutorType(),
                null, false);
    }

    public SqlSession openSession(
            boolean autoCommit) {
        return openSessionFromDataSource(
                configuration
                        .getDefaultExecutorType(),
                null, autoCommit);
    }

    public SqlSession openSession(
            ExecutorType execType) {
        return openSessionFromDataSource(
                execType, null, false);
    }

    public SqlSession openSession(
            TransactionIsolationLevel level) {
        return openSessionFromDataSource(
                configuration
                        .getDefaultExecutorType(),
                level, false);
    }

    public SqlSession openSession(
            ExecutorType execType,
            TransactionIsolationLevel level) {
        return openSessionFromDataSource(
                execType, level, false);
    }

    public SqlSession openSession(
            ExecutorType execType,
            boolean autoCommit) {
        return openSessionFromDataSource(
                execType, null,
                autoCommit);
    }

    public SqlSession openSession(
            Connection connection) {
        return openSessionFromConnection(
                configuration
                        .getDefaultExecutorType(),
                connection);
    }

    public SqlSession openSession(
            ExecutorType execType,
            Connection connection) {
        return openSessionFromConnection(
                execType, connection);
    }

    public Configuration getConfiguration() {
        return configuration;
    }

    private SqlSession openSessionFromDataSource(
            ExecutorType execType,
            TransactionIsolationLevel level,
            boolean autoCommit) {
        Transaction tx = null;
        try {
            final Environment environment = configuration
                    .getEnvironment();
            final TransactionFactory transactionFactory = getTransactionFactoryFromEnvironment(environment);
            tx = transactionFactory
                    .newTransaction(
                            environment
                                    .getDataSource(),
                            level,
                            autoCommit);
            final Executor executor = configuration
                    .newExecutor(tx,
                            execType);
            return new DefaultSqlSession(
                    configuration,
                    executor,
                    autoCommit);
        } catch (Exception e) {
            closeTransaction(tx); // may have fetched a connection so lets call
            // close()
            throw ExceptionFactory
                    .wrapException(
                            "Error opening session.  Cause: "
                                    + e,
                            e);
        } finally {
            ErrorContext.instance()
                    .reset();
        }
    }

    private SqlSession openSessionFromConnection(
            ExecutorType execType,
            Connection connection) {
        try {
            boolean autoCommit;
            try {
                autoCommit = connection
                        .getAutoCommit();
            } catch (SQLException e) {
                // Failover to true, as most poor drivers
                // or databases won't support transactions
                autoCommit = true;
            }
            final Environment environment = configuration
                    .getEnvironment();
            final TransactionFactory transactionFactory = getTransactionFactoryFromEnvironment(environment);
            final Transaction tx = transactionFactory
                    .newTransaction(connection);
            final Executor executor = configuration
                    .newExecutor(tx,
                            execType);
            return new DefaultSqlSession(
                    configuration,
                    executor,
                    autoCommit);
        } catch (Exception e) {
            throw ExceptionFactory
                    .wrapException(
                            "Error opening session.  Cause: "
                                    + e,
                            e);
        } finally {
            ErrorContext.instance()
                    .reset();
        }
    }

    private TransactionFactory getTransactionFactoryFromEnvironment(
            Environment environment) {
        if (environment == null
                || environment
                .getTransactionFactory() == null) {
            return new ManagedTransactionFactory();
        }
        return environment
                .getTransactionFactory();
    }

    private void closeTransaction(
            Transaction tx) {
        if (tx != null) {
            try {
                tx.close();
            } catch (SQLException ignore) {
                // Intentionally ignore. Prefer previous error.
            }
        }
    }

}
